JPH06276410A - Level correction device - Google Patents

Abstract

PURPOSE:To correct the level of an amplitude of a high vision signal. CONSTITUTION:The level correction device corrects an amplitude level of a high vision signal in which a level standard signal having an identification signal and a level reference signal is inserted in a predetermined line and is provided with an identification signal detection means 3 detecting an identification signal, 1st and 2nd level detection means 1, 2 detecting 1st and 2nd reference levels, and an AGC means 6 correcting the amplitude level of the high vision signal based on a reference level relating to the line on which the identification signal is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a level correction device.

[0002]

2. Description of the Related Art In recent years, high-definition signals (hereinafter referred to as "HD
Signal ”is abbreviated. ), A wideband high-definition video signal having a large number of scanning lines as compared with a conventional video signal such as an EDTV signal is known. In equipment that handles high definition video signals,
Since digital processing is often performed and the dynamic range is strictly limited in digital processing, it is important to manage the amplitude level of the signal.

As a method of managing the amplitude level of the video signal, a method of detecting the amplitude level of the synchronizing signal and managing the amplitude level of the video signal based on the detection result has been conventionally known.

[0004]

However, in digital processing performed in a device that handles a high definition video signal, the synchronization signal is often deleted to perform processing in order to save memory. Therefore, there is a problem that accurate level correction cannot be performed if the level correction of the high definition video signal is performed only based on the amplitude level of the synchronization signal.

Further, in a high-definition VTR, which is a type of equipment that handles high-definition video signals, an inversion phenomenon occurs in a reproduced image because the HD signal level is too high.
There is a problem that the reproduced image has a low contrast because the level is too low.

[0006]

The present invention provides the following configurations in order to solve the above problems.

A level correction device for correcting the amplitude level of a high definition video signal in which a level standard signal having an identification signal and a level reference signal is inserted in a predetermined line, and a discrimination for detecting the identification signal. Signal detection means, level detection means for detecting the reference level of the level reference signal, and correction for correcting the amplitude level of the high definition video signal based on the reference level of the line in which the identification signal is detected A level correction device having a means.

A level correction device for correcting the amplitude level of a high definition video signal in which a level standard signal having an identification signal and a level reference signal is inserted in a predetermined line, and an identification for detecting the identification signal. The signal detecting means, the line discriminating means for identifying the predetermined line, the level detecting means for detecting the reference level of the level reference signal, and the identification signal on the line identified by the line discriminating means. At this time, a level correction device having a correction means for correcting the amplitude level of the high definition video signal on the basis of the reference level of the specified line.

A level correction device for correcting the amplitude level of a high-definition video signal in which a level standard signal having an identification signal and a level reference signal is inserted in a predetermined line. A signal detecting means, a line discriminating means for specifying the predetermined line, a level detecting means for detecting a reference level of the level reference signal, and a sink for detecting an amplitude level of a sync signal related to the high definition video signal. When the identification signal is detected on the line specified by the level detection means and the line determination means, the amplitude level of the high definition video signal is corrected based on the reference level of the specified line, If the identification signal is not detected on the line identified by the line discriminating means, the amplitude level of the sync signal detected by the sync level detecting means is set to the amplitude level. Zui and level correction device having a correcting means for correcting the amplitude level of the high definition video signal.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a waveform diagram of a level standard signal, and FIG. 2 is an HD.
FIG. 3 is a waveform diagram for explaining the line of the level standard signal inserted in the signal, FIG. 3 is a block diagram for explaining the main part of the level correction apparatus according to the first embodiment, FIG. 4 is the timing chart of FIG. FIG. 5 is a block diagram for explaining the main part of the level correction apparatus according to the second embodiment, and FIG.
A flow chart for explaining an example of a level correction method when a level standard signal is inserted in 3,604 lines, and FIG. 7 is a block diagram for explaining a main part of a level correction apparatus according to a third embodiment. FIG. 8 is a waveform diagram of the horizontal synchronizing signal, FIG. 9 is a block diagram and timing chart of the timing generating means, and FIG. 10 is another example of the level correction method when the level standard signal is inserted in the lines 603 and 604. 11 is a block diagram of a high-definition VTR according to the present invention. This embodiment takes an HD signal as an example of a high definition video signal, detects a level standard signal inserted in a predetermined line of the HD signal, and corrects the amplitude level of the HD signal based on this. is there. Embodiments will be described below with reference to the drawings. First, a presupposed level standard signal and a line on which the level standard signal is inserted will be described.

The level standard signal has an identification signal and a level reference signal, but the following modes are possible. For example, the level standard signal shown in FIG.
The horizontal synchronizing signal is inserted in the period T1, the identification signal is inserted in the subsequent period T2, and the level reference signal is inserted in the subsequent period T3. The horizontal synchronizing signal is inserted in a predetermined line of the HD signal. ing. This identification signal is, for example, a 2-bit signal, and the level reference signal is composed of 100% level, 50% level, and 0% level.

Further, in the level standard signal shown in FIG. 1B, not only the level information but also 12-bit information relating to the contents of the HD signal is multiplexed in the level reference signal (period T3). 100% level, low level is 0
Represents the% level.

In the level standard signal shown in FIG. 1C, the identification signal and the level reference signal are used in common, and the period T
2 and T3 are inserted, and a normal picture signal is inserted in a period T4 that follows. It should be noted that the interference on the screen can be prevented by keeping the periods T2 and T3 in FIG. 6C within the horizontal overscan period of the monitor.

Further, in the level standard signal shown in FIG. 1D, a level reference signal is inserted in a period T3 which is a horizontal overscan period of the monitor following a period T4 in which a normal picture signal is inserted. ing.

These level standard signals are shown in FIG.
41 to 66 lines of HD signals shown in FIG.
~ 557 lines, 603 lines ~ 628 lines and 10
It is inserted in one line or a plurality of lines out of 95 lines to 1120 lines. The level standard signal is inserted in the relevant line because it is necessary to insert the level standard signal in the effective scanning line because the sync signal period such as the vertical sync signal and the horizontal sync signal may be deleted by the high-definition device. This is because the monitor has an overscan characteristic of 8% to 10% for all the scanning lines so that the level standard signal is not displayed on the screen.

High-definition equipment for correcting the level of an HD signal based on such a level standard signal is shown in FIGS.
1 will be described below. Although the signal shown in FIG. 1A is taken as an example of the level standard signal here, it goes without saying that the level standard signal shown in FIGS. 1B to 1D may be used.

(First Embodiment) In FIG. 3, an input HD signal aa is supplied to the level detecting means 1 and 2 and the identification signal detecting means 3 from a transmission line (not shown). Here, the input HD signal aa is one type of Y, PB and PR signals, and
The signal complies with the domestic high-definition signal standard, and is a signal converted from the R, G, B signals by the following formula.

Y = 0.7154G + 0.0721B + 0.2125R PB = 0.5389 (-0.7154G + 0.9279B-0.2125R) PR = 0.6349 (-0.7154G-0.0721B + 0.7875R) First, the identification signal detecting means 3 inputs the HD signal aa. The identification detection signal 3a obtained by detecting the identification signal in the level standard signal inserted in the predetermined line is supplied to the timing generation means 4. That is, the identification signal inserted in the period T2 in the level standard signal shown in FIG. 4A is detected to obtain the identification detection signal 3a shown in FIG. There is. Here, the identification signal is detected because the predetermined line in which the level standard signal is inserted is a line related to the effective scanning line, and therefore the pattern signal is usually inserted, so that the pattern signal is inserted. This is because it is necessary to specify the line in which the level standard signal is inserted instead of.

Then, the timing generation means 4 delays the discrimination detection signal 3a by a predetermined time, and then, in FIG.
The first and second sample signals 4a and 4b shown in FIG.
Then, these signals are supplied to the first and second level detecting means 1 and 2, where the first and second sample signals 4
The first and second level detection signals 1a and 2a obtained by sampling the level reference signal in the level standard signal while a and 4b are at the high level are supplied to the first comparison means 5.

The first comparing means 5 subtracts the second level detection signal 2a corresponding to the 0% level of the level reference signal from the first level detection signal 1a corresponding to the 100% level of the level reference signal. The obtained value is compared with a predetermined reference value, and the first level control signal 5a generated based on the result is supplied to the AGC means 6.

Then, the AGC means 6 uses the first level control signal 5a to vary the amplification factor so that the input HD signal aa has a normal amplitude level, thereby obtaining the output HD signal bb, which is not shown. Or it is output to the latter stage of the high-definition device. When the first and second level detection signals 1a and 2a are not present, the first level control signal 5a is a signal having a predetermined value such that the amplification factor of the AGC means 6 is "1".

In this way, since the identification signal is detected and the AGC means 6 is substantially operated only when the identification signal is detected, the reference level (100% level) of the level standard signal in the input HD signal aa is determined. , 0% level), the amplitude level of the input HD signal aa can be corrected.

When the input HD signal aa is clamped at a predetermined clamp level, the second level detecting means 2 is unnecessary and the first level detection signal 1a is compared with a predetermined reference value. Of course, the first level control signal 5a may be obtained. In such a case, the clamp timing may be, for example, a period immediately after the ternary synchronization signal as shown in FIG.

(Second Embodiment) In the first embodiment, the identification signal is detected and the line in which the level standard signal is inserted is specified. However, in the line related to the picture signal,
If the waveform in the period corresponding to the identification signal period is substantially the same as the identification signal, it is erroneously detected as a line in which the level standard signal is inserted although it is a line related to the picture signal. In some cases. Therefore, in the second embodiment, the line in which the level standard signal is to be inserted is specified by the line judging means, and it is judged whether or not the line specified as a result has an identification signal.

In FIG. 5, the same components as those in FIG. 4 are designated by the same reference numerals, and the line discriminating means 7 different from FIG. 4 will be described here. The input HD signal aa is supplied to the line discriminating means 7, where the input HD signal a
The sync signal related to a is separated, and the high level is maintained during the period in which the number of the sync signals counted and the number of lines in which the predetermined level standard signal is inserted match,
Obtain the line discrimination signal 7a that becomes a low bell during the other period,
This signal is supplied to the timing generation means 4.

Then, the timing generation means 4 generates the first and second sample signals 4a and 4b only when the identification detection signal 3a becomes high level during a predetermined period in which the line discrimination signal 7a becomes high level. ing. For example, the line discrimination signal 7a and the identification detection signal 3a may be input to the AND circuit, and the output signal thereof may be delayed for a predetermined time to generate the first and second sample signals 4a and 4b.

In this way, the level correction is performed by using the information of the line in which the level standard signal should be inserted. Therefore, the level correction is not performed even though the level standard signal is not inserted. Therefore, surely input HD signal a
The amplitude level of a can be corrected.

Now, the lines 41, 557, 603, 1120 and the lines 42, 604, 557, 1121 as lines through which the level standard signal is inserted are particularly important lines for the following reasons.

As described above, the level standard signal is 41 to 66 lines, considering that the monitor has 8% to 10% overscan for all the scanning lines.
The number of scanning lines that the monitor overscans actually varies depending on each device, although it is inserted in one line or a plurality of lines among 532 to 557 lines, 603 to 628 lines, and 1095 to 1120 lines. Therefore, it is desirable to insert the level standard signal into a scanning line which is an effective scanning line and which is unlikely to appear on the screen.

By the way, in the HD signal of the studio standard, there are 1035 effective scanning lines, and the effective picture period is 41 lines to 557 lines and 603 lines to 1120.
Since it is a line, 41,557,603,1120 lines are the lines satisfying the above conditions, while the MUS
Since there are 1032 effective scanning lines in the E decoder output signal and the effective picture period is 42 lines to 557 lines and 604 lines to 1119 lines, 42, 55
Lines 7,604,1119 are lines satisfying the above conditions.

Therefore, as the input signal of the level correcting apparatus according to the present embodiment, the input HD signal aa is 41,55.
It is necessary to consider two types of signals: a signal in which the level standard signal is inserted in lines 7,603,1120 and a signal in which the level standard signal is inserted in lines 42,557,604,1119. . So 603 lines, 6
A level correction method and apparatus in the case of assuming two kinds of signals in which level standard signals are respectively inserted in 04 lines will be described in detail with reference to FIGS.

In FIG. 6, starting from step S1,
In step S2, it is determined whether or not there is an identification signal on line 603. Specifically, the line discriminating means 7 in FIG. 5 identifies 603 lines, and the discrimination signal detecting means 3 and the timing generating means 4 detect whether or not there is an discrimination signal on the 603 lines. Then, when step S2 ends, if there is an identification signal, the process proceeds to step S4, while if there is no identification signal, the process proceeds to step S3.

In step S3, it is determined whether or not there is an identification signal on the 604th line. Specifically, the line discriminating means 7 in FIG. 5 identifies 604 lines, and the discrimination signal detecting means 3 and the timing generating means 4 detect whether or not there is an discrimination signal on the 604 lines. Then, when step S3 ends, if there is an identification signal, the process proceeds to step S4, while if there is no identification signal, step S3.
Go to 2.

In step S4, 603 lines or 60
Level correction is performed based on the level standard signals inserted in the four lines. Specifically, the first level control signal 5a generated by the first comparison means 5 based on the first and second level detection signals 1a and 2a in FIG. 5 is supplied to the AGC means 6, At, the amplitude level of the input HD signal aa is corrected to a normal amplitude level. When step S4 ends, the process returns to step S2 and these steps are repeated.

In this way, in performing the level correction based on the level standard signal, the 603 line can be prioritized over the 604 line. Of course, with respect to the 41st line and the 42nd line, the younger line may be prioritized as described above. Also, 6 after the 604 line
Of course, it may be configured to determine whether or not the identification signal is inserted in the 05 line, repeat this for 628 lines, and give priority to the young line.

(Third Embodiment) In the first and second embodiments, the line related to the picture period is assumed as the line through which the level standard signal is to be inserted. This is because the high-definition equipment performs digital processing. This is because it is considered that the signal is often deleted. Therefore, in the second embodiment, the level standard signal is specified by using the information of the line in which the level standard signal is to be inserted and the information on the presence / absence of the identification signal, and if it cannot be specified, the level correction is not performed. Was there.

However, the level standard signal is not inserted in the output of the high-definition camera which is the source of the current HD signal, and the level standard signal is not necessarily inserted in all HD signals. Therefore, it should be assumed that a signal in which the level standard signal is inserted and a signal in which the level standard signal is not inserted are supplied to the high-definition equipment. On the other hand, there are also high-definition devices such as signal cables, amplifiers, distributors, etc. that perform analog processing without deleting the synchronization signal, so it is not meaningless to make level correction based on the synchronization signal.

Therefore, in the present embodiment, assuming such a case, when the level standard signal is inserted, priority is given to the level standard signal and level correction is performed based on this, so that the level standard signal is If it is not inserted, level correction is performed based on the horizontal synchronization signal.

In FIG. 7, the same components as those in FIG. 5 are designated by the same reference numerals. Here, the differences from FIG. 5 are the sync level detecting means 8, the second comparing means 9, and the selecting means 1.
0 and the selection signal 4 output from the timing generation means 4
c will be described.

This sync level detecting means 8 is used for input HD
The amplitude level of the horizontal synchronizing signal of the signal aa is detected. For example, the difference V1 between the sync peak level and the sync tip level of the horizontal synchronizing signal shown in FIG. 8 or the difference V2 between the sync peak level and the pedestal level. Is supplied to the second comparing means 9.

Then, the second comparing means 9 supplies the second level control signal 9a obtained by comparing the sync level detection signal 8a with a predetermined reference sync level to the selecting means 9.

When the level standard signal is inserted, the selecting means 9 preferentially selects and outputs the first level control signal 5a. On the other hand, when the level standard signal is not inserted, the selecting means 9 outputs the first level control signal 5a. Selects and outputs the second level control signal 9a and is controlled by the selection signal 4c.

Here, the structure of the timing generation means 4 for generating the selection signal 4c will be described in detail with reference to FIG. Figure 9
In (A), the reset terminal R of the D flip-flop 40 is supplied with the reset signal 40a shown in (C) of the figure which is obtained by extracting the rising edge of the line discrimination signal 7a shown in (B) of the figure. The line discrimination signal 7a is a signal which is at a high level for a predetermined line,
For example, when the lines 603 to 610 correspond to a predetermined line, the high level starts from the start of the 603 line and the high level is maintained until the end of the 610 line.
This signal is low level from the start of line 11 to the start of line 603 related to the next frame.

Since the identification detection signal 3a shown in FIG. 3D is supplied to the clock terminal of the D flip-flop 40, the output signal 40 of the D flip-flop 40.
b is the signal shown in FIG. The output signal 40b is the data terminal D of the D flip-flop 41.
The output signal 40b is latched by a signal obtained by inverting the line discrimination signal 7a supplied to the clock terminal by the inverter 42, and the selection signal 4c shown in FIG.

The selecting means 10 (shown in FIG. 7) selectively outputs the first level control signal 5a while the selection signal 4c is at the high level and the second level control signal 9a during the low level period. ing.

In this way, the AGC means 6 operates on the basis of the signal thus obtained, so that when the level standard signal is inserted, the level standard signal is given priority and the level correction is performed based on this. When the level standard signal is not inserted, level correction can be performed based on the horizontal synchronizing signal.

Now, as in the second embodiment, the input HD
7 and 10 for the level correction method and apparatus assuming a signal in which the level standard signal is inserted in the line 603 and a signal in which the level standard signal is inserted in the line 604 as the signal aa. The description will be made with reference.
In FIG. 10, the same components as those in FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 10 differs from FIG. 6 in step S5.
Is the newly added point. That is, first, step S
It is determined in step 2 whether or not an identification signal is present in the 603 line, then in step S3 it is determined whether or not an identification signal is present in the 604 line, and if there is no identification signal in the 603 and 604 lines, Only step 5 will be executed.

This step S5 corrects the level of the input HD signal based on the amplitude level of the horizontal synchronizing signal. Specifically, the sync level detecting means 8 and the second comparing means in FIG. It is composed of a selection means 10 and an AGC means. Then, when step S5 ends, the process returns to step S2, and steps S2 to S5 are repeated.

In this way, when the level of the input HD signal aa is corrected, the level standard signal inserted in the 603 line is given priority, and the level standard signal inserted in the 604 line is given priority. If there is no level standard signal in either of them, the level can be corrected based on the amplitude level of the horizontal synchronizing signal. It is needless to say that the younger lines may be prioritized as described above for the 41st line and the 42nd line. Further, it is of course possible to determine whether or not the identification signal is inserted in the 605 line subsequent to the 604 line, repeat this for 628 lines, and give priority to the young line.

(Fourth Embodiment) In the first to third embodiments, the level correction apparatus alone or the level correction apparatus generally applicable as a part of high-definition equipment such as a monitor and an electronic editing apparatus has been described. The fourth embodiment,
A case where this is applied to a high definition VTR will be described. In the fourth embodiment, the first to third embodiments
Each of the level correction devices described in the embodiments will be referred to as level correction means.

In FIG. 11, the above-mentioned input HD signal a
Y, PB, PR signals a1, a2, a3 corresponding to a are A
Level correction means 15-1 via the / D converters 12-14
7 where the amplitude level correction is performed digitally and then the non-linear emphasis means 18-20.
The output signals of the level correcting means 15 to 17 are supplied to.

Since the non-linear emphasis means 18 to 20 emphasize the high frequency components in comparison with the low frequency components in accordance with the amplitude level of the input signal, they are provided after the level correcting means 15 to 17 as shown in the figure. It is provided in. Then, the output signals of the non-linear emphasis means 18 to 20 are supplied to the dividing means 21, where the first Y, PB, PR signals 21a to 21c and the second Y, PB and PR signals obtained by dividing into two systems are obtained.
The PB and PR signals 21d to 21f are supplied to the first and second recording processing means R1 and R2. Since the second recording processing means R2 has the same configuration as the first recording processing means R1, its explanation is omitted.

Then, the first PB and PR signals 21 supplied to the line-sequential conversion means 23 in the first recording processing means R1.
a is subjected to line-sequential processing, converted into a line-sequential color signal, and TC
It is supplied to one input of the I conversion means 22. Then, the line-sequential color signal is time-axis-compressed by the TCI converting means 22 and the first Y signal 21a supplied to the other input is time-axis-compressed.
Straight line emphasis means 2 for I signal via D / A converter
5 is being supplied.

The linear emphasis means 25 relatively emphasizes the horizontal high frequency component of the TCI signal with respect to the low frequency component, and supplies it to the FM modulation means 26. Then, the FM modulator 26 performs FM modulation by a predetermined deviation, and the output signal is amplified by a recording amplifier (not shown) and then recorded on the magnetic tape T via the magnetic heads 1A and 1B.

In this way, in the magnetic recording apparatus according to the present embodiment, the Y, PB and PR signals a1, a2 and a3 are level-corrected by the level correcting means 15 to 17, so that accurate non-linear emphasis is performed. Moreover, since the FM modulation means does not cause overmodulation, no inversion phenomenon occurs in the reproduced image, and the Y, PB and PR signals a
Since the amplitude levels of 1, a2 and a3 can be recorded appropriately, a reproduced image with contrast can be obtained.

In the fourth embodiment, the A / D converter 1
2 to 14 and the level correcting means 15 to 17 may be replaced with each other. In such a case, the level correcting means 15 to 17 of course perform analog processing.

[0058]

As described above, according to the configuration of the present invention,
In particular, since it has a correcting means for correcting the amplitude level of the high-definition video signal based on the reference level related to the line in which the identification signal is detected, the level standard signal can be inserted in the effective scanning line. Even if it is a high-definition video signal obtained through a high-definition video signal device in which the synchronization signal is deleted by the processing, its amplitude level can be reliably corrected.

Further, as described above, according to the configuration of the present invention, particularly when the identification signal is detected in the line specified by the line discriminating means, the high level is set based on the reference level of the specified line. Since the correction means for correcting the amplitude level of the definition video signal is provided, the level reference signal is specified by using not only the identification signal but also information of a predetermined line through which the level standard signal should be inserted. Therefore, it is possible to correct the amplitude level of the high definition video signal.

Further, as described above, according to the configuration of the present invention, particularly when the identification signal is detected in the line identified by the line discriminating means, the high definition is performed based on the reference level of the identified line. If the identification signal is not detected on the line identified by the line discriminating means, the high-definition video signal is corrected based on the amplitude level of the synchronizing signal detected by the sync level detecting means. Since it has a correction means for correcting the amplitude level of the video signal, the level standard signal can be prioritized when the level standard signal is inserted, and the amplitude level of the synchronization signal can be corrected when the level standard signal is not inserted. Since the amplitude level can be corrected based on the level, there is an effect that the amplitude level of the high definition video signal can be corrected based on more appropriate information.

[Brief description of drawings]

FIG. 1 is a waveform diagram of a level standard signal.

FIG. 2 is a waveform diagram for explaining a line of a level standard signal inserted in an HD signal.

FIG. 3 is a block diagram for explaining a main part of the level correction apparatus according to the first embodiment.

FIG. 4 is a timing chart of FIG.

FIG. 5 is a block diagram for explaining a main part of a level correction device according to a second embodiment.

FIG. 6 is a flowchart illustrating an example of a level correction method when a level standard signal is inserted in lines 603 and 604.

FIG. 7 is a block diagram illustrating a main part of a level correction device according to a third embodiment.

FIG. 8 is a waveform diagram of a horizontal synchronizing signal.

9A and 9B are a block diagram and a timing chart of a timing generation unit.

FIG. 10 is a flowchart for explaining another example of the level correction method when a level standard signal is inserted in lines 603 and 604.

FIG. 11 is a block diagram of a high-definition VTR according to the present invention.

[Explanation of symbols]

1, 2nd 1st, 2nd level detection means (level detection means) 3 identification signal detection means 6 AGC means (correction means) 7 line determination means 8 sync level detection means aa input HD signal (high definition video signal)

Claims (3)

[Claims] 1. A level correction device for correcting the amplitude level of a high definition video signal in which a level standard signal having an identification signal and a level reference signal is inserted in a predetermined line, and detecting the identification signal. Identification signal detecting means for detecting the reference level of the level reference signal, and the amplitude level of the high definition video signal based on the reference level of the line in which the identification signal is detected. High-definition video signal level correction apparatus having a correction means for performing. 2. A level correction device for correcting the amplitude level of a high definition video signal in which a level standard signal having an identification signal and a level reference signal is inserted in a predetermined line, and detecting the identification signal. Identifying signal detecting means, line identifying means for identifying the predetermined line, level detecting means for detecting a reference level of the level reference signal, and the identifying signal detected by the line identified by the line identifying means. And a correction unit that corrects the amplitude level of the high definition video signal based on the reference level of the specified line. 3. A level correction device for correcting the amplitude level of a high definition video signal in which a level standard signal having an identification signal and a level reference signal is inserted in a predetermined line, and detecting the identification signal. Identification signal detecting means, a line discriminating means for specifying the predetermined line, a level detecting means for detecting a reference level of the level reference signal, and an amplitude level of a synchronizing signal for the high definition video signal. And a sync level detecting means for correcting the amplitude level of the high definition video signal based on the reference level of the specified line when the identification signal is detected on the line specified by the line determining means. However, if the identification signal is not detected on the line identified by the line discriminating means, the amplitude level of the sync signal detected by the sync level detecting means is detected. Level correction device having a correcting means for correcting the amplitude level of the high-definition video signal on the basis of.